Energy

Energy champions use an alternative to mana for spending on abilities. Having a maximum of 200 energy (except for Shen with 400 energy) with no growth per level, the main advantage of energy is its rapid regeneration (10 energy per second), so that energy champions are not at the risk of depleting their resource over an extended period of time. The main disadvantage of energy is that its small capacity restricts the rapid usage of multiple spells in a short period of time. The energy resource bar is colored yellow.

Ferocity

Rengar generates 1 Ferocity whenever he casts a basic ability. Upon reaching 4 Ferocity, his next basic ability is empowered, can be cast independently of its basic version's cooldown, incurs no cooldown of its own and consumes all of his Ferocity.

While Rengar has between 1 and 3 Ferocity, the sections are colored white. Upon reaching 4 Ferocity, the sections are colored orange.

Fury

Fury behaves uniquely on each champion that utilizes it. The only consistent features are that each champion can generate fury on-hit or with their abilities, the limit is 100 and the resource bar is colored red (not necessarily all the time).

While in Mini Gnar form, Gnar generates Fury over 3 seconds upon dealing or receiving damage. Also every time he damages at least one enemy with a basic attack or Boomerang Throw he generates Fury, quadrupled amount against champions. Gnar's Fury decays if he has not dealt or received damage in the last 13 seconds.

When Mini Gnar reaches 100 Fury, he gains access to an alternate set of abilities, which share his abilities' cooldowns. After either 5 seconds or upon casting an ability, Gnar transforms into Mega Gnar for 15 seconds while his Fury depletes. Once his Fury is exhausted, Gnar reverts into Mini Gnar, retaining the same health percentage, and becomes Tired out for 15 seconds, during which he cannot gain Fury.

Rek'Sai generates Fury every time she lands a basic attack, Queen's Wrath, Unburrow or Furious Bite, plus additional Fury per enemy hit beyond the first. Rek'Sai loses 20 Fury per seconds if she has not gained any in the last 5 seconds.

As long as Rek'Sai remains burrowed, she expends 20% of her accumulated Fury every second to heal herself, up to a maximum of 25 - 450 (based on level) over 5 seconds if she burrowed at 100 Fury. This stops once Rek'Sai consumes all of her Fury or returns to full health.

Furious Bite: Rek'Sai bites the target enemy, dealing physical damage that is increased by 1% for every point of current Fury. If Rek'Sai has full Fury, Furious Bite deals true damage instead.

Renekton generates Fury with his basic attacks and abilities. His ultimate, Dominus, also generates Fury over time for 15 seconds. He loses 4 Fury per second if he hasn't dealt or received damage in the last 12 seconds.

At 50 or more Fury, his next basic ability consumes 50 Fury to enhance its effects, though generating no Fury in the process.

Renekton gains 50% more Fury from all sources while below half health.

Tryndamere gains Fury each time he lands a basic attack, doubled on critical strikes. He also generates Fury for each enemy hit with Spinning Slash, each time he kills an enemy, and when under the effect of Undying Rage. After not dealing or receiving damage for 8 seconds, Tryndamere loses Fury each second.

Tryndamere gains 0.35% critical strike chance per point of Fury he currently has, up to a maximum of 35% critical strike chance.

Bloodlust: Tryndamereheals himself, consuming all Fury. Each Fury he currently has increases the heal.

Health

These champions use their own health to cast some — or all — of their abilities. Champions can never kill themselves due to ability casting, as their abilities become free at critical levels of health. While these champions can cast their abilities more freely than most, their disadvantage is that frequent ability usage will bring them closer to death. With the exception of Dr. Mundo'sSadism, the ultimate abilities of health-using champions are free of any cost; only gated by cooldown.

It's worth noting that all of these champions have at least one ability capable of restoring their health:

Dr. Mundo'sSadism costs 20% of current health to cast, but restores 40 / 50 / 60% of his maximum health over 12 seconds.

Mordekaiser'sChildren of the Grave is cost-free and heals for 24 / 29 / 34% (+ 4% per 100 AP) of target's maximum health in a period of 10 seconds: half that amount instantly and the other half over 10 seconds.

Heat

Heat is generated whenever he casts one of his basic abilities. Heat rapidly depletes if Rumble has not cast an ability in the last 4 seconds. Rumble gains different effects depending on his current Heat. Heat is displayed in Rumble's secondary resource bar, and is colored differently depending on the current amount.

Overheating:100 HEAT: Rumble is silenced and his basic attacks deal additional damage until his heat reaches 0. Visually Rumble's mech is colored bright red and you can hear his cries of discomfort due to the heat.

Other uses of the secondary bar

Some champions use the secondary bar to display some ability effects to track them better.

Blood

Blood Well acts as a health reserve used when Aatrox takes lethal damage - reviving him with an amount of health equal to the Blood Well's contents plus a base amount. The revival effect has a cooldown, and the current amount in the reserve is colored red or white depending on whether or not the effect is available. Aatrox fills the Blood Well by casting his abilities, with 100% of the health cost being stored in the Blood Well. The blood slowly depletes if Aatrox has not taken or dealt damage recently.

Aatrox also gains bonus attack speed based on the contents of his current Blood Well, regardless of whether the revival effect is available.

Courage

Kled is accompanied by his semi-trusty mount, Skaarl. Depending of whether Kled is mounted or dismounted from Skaarl, his set of abilities is altered.

Whenever Kled get dismounted he gains the ability to restore Skaarl'sCourage to reunite again, which is displayed in Kled's resource bar.

Kled restores Courage on takedowns and for dealing damage. At 100 Courage, Skaarl returns to the fight with 50 / 60 / 70 / 80% of his health. Returning to the base fully restores Skaarl's Courage and health. If reuniting outside of base Skaarl gains Frayed Nerves, and a dismountedKled will not be able to restore Skaarl's Courage for a brief period of time.

Trivia

It is currently being considered to have Riven'sRunic Blade charges displayed in the resource bar, in a visually similar manner to Rengar's Ferocity.[1] If this change passes, similar changes may also be applied to similar mechanics (such as Tides of Blood).

When the mechanic was unique to Renekton, Fury was known as "Rage".

When HUD animations were first revealed on the PBE, Tryndamere, Shyvana and Renekton's resources were described as Battle Fury, Dragon Fury and Rage, respectively.[2]

Gnar's Fury is listed within the game files as "Tantrum".

When Riven was first released, she was not technically classified as manaless - she simply had 0 (+0) base mana and 0 (+0) base mana regeneration. She could purchase mana and it would be represented in her resource bar - allowing her to use and benefit from items such as Manamune and Archangel's Staff. This was hotfixed shortly after.